Polyurethane Adhesive

ABSTRACT

The present invention relates to acrylic compositions capable of bonding directly with an isocyanate-containing composition, e.g. polyurethane, and methods for manufacturing the same. The acrylic compositions of the invention have multifunctional chain transfer agents and/or multifunctional crosslinkers with isocyanate-reactive groups.

FIELD OF THE INVENTION

This invention relates to methods for manufacturing an articlecomprising an acrylic composition. In particular, this invention relatesto methods for manufacturing an article comprising (1) an acryliccomposition having a multifunctional chain transfer agent; and (2) anisocyanate-containing composition, for example, polyurethane.

BACKGROUND OF THE INVENTION

An article that comprises an acrylic composition and has an acceptablerigidity is a highly desired commercial feature.

One method known in the art to obtain this rigidity is using fiberreinforced plastic (FRP). FRP articles are well known in the art forproviding rigidity to articles comprising an acrylic composition. Aproblem, however, is that the application of FRP is labor intensive,involving the rolling and pushing of it onto the back of a polymer.Also, the application of FRP presents major environmental concernsbecause it emits high levels of styrene during the application andcuring of FRP.

Another way known in the art to increase rigidity of an acryliccomposition is to apply polyurethane. However, polyurethane directlyapplied to an acrylic composition does not adhere well. Therefore, it isknown in the art that acrylonitrile-butadiene styrene (ABS) may belaminated to the back of an acrylate polymer prior to applyingpolyurethane. This lamination step with ABS provides adhesion so thatpolyurethane may subsequently be applied to it, creating a three layersystem having rigidity. This extra step of adding ABS is costly and,time and labor intensive.

Thus a need exists for a method for manufacturing an acrylic compositionthat exhibits good adhesion directly to polyurethane.

SUMMARY OF THE INVENTION

In one aspect, the invention provides acrylic compositions capable ofbonding directly with an isocyanate-containing composition, e.g.polyurethane, and methods for manufacturing the same. Another aspect ofthe invention provides a method for benefitting from such acryliccompositions wherein the benefit includes receiving a profit, supplying,and/or otherwise introducing such compositions into commerce.

In another aspect, the invention provides acrylic compositions having amultifunctional chain transfer agent capable of bonding directly with anisocyanate-containing composition, and methods for manufacturing thesame.

In another aspect, the invention provides acrylic compositions having amultifunctional chain transfer agent with an isocyanate-reactive groupin a sufficient amount to bond directly to an isocyanate-containingcomposition, and methods for manufacturing the same.

In another aspect, the invention provides articles comprising a cured orsubstantially cured acrylic composition directly bonded to polyurethane,and methods for manufacturing the same. Another aspect of the inventionprovides a method for benefitting from such articles wherein the benefitincludes receiving a profit, supplying, and/or otherwise introducingsuch articles into commerce.

In another aspect, the invention provides articles comprising an acryliccomposition bound to a polyurethane composition, the acrylic compositionhaving bound therein an effective amount of a chain transfer agent andat least one residue thereof, wherein the chain transfer agent residuecomprises a reacted isocyanate-reactive group that has reacted with anisocyanate bound within the polyurethane composition.

In another aspect, the invention provides articles comprising cured orsubstantially cured acrylic composition having a multifunctional chaintransfer agent or residue thereof directly bound toisocyanate-containing composition, and methods for manufacturing thesame.

In another aspect, the invention provides for articles comprising a bond(e.g. a carbamate bond, a thiocarbamate bond, a carbamide bond, or anyother bonds) between an acrylic composition and a polyurethanecomposition wherein the bond is formed between the residue of amultifunctional chain transfer agent bound within the acryliccomposition and a residue of an isocyanate bound within theisocyanate-containing composition, and methods for manufacturing thesame.

In another aspect, the invention provides methods for manufacturingarticles comprising binding an acrylic composition to a polyurethanesubstrate. In another aspect, the invention provides methods formanufacturing articles comprising binding an acrylic composition to apolyurethane substrate where the bonding occurs after coating and/orcoextruding an acrylic composition onto a polyurethane substrate.

In another aspect, the invention provides methods for manufacturingarticles comprising binding polyurethane to an acrylic compositionsubstrate. In another aspect, the invention provides methods formanufacturing articles comprising binding polyurethane to an acryliccomposition substrate where the bonding occurs after applying a mixtureof an isocyanate-containing composition to a cured or substantiallycured acrylic composition substrate, for example, by spraying orcontacting the isocyanate-containing composition onto the acryliccomposition substrate.

In another aspect, the invention provides methods for manufacturingarticles comprising formulating a cured or partially cured acryliccomposition having bound within the acrylic polymer matrix amultifunctional chain transfer agent with an isocyanate-reactive group.

In another aspect, the invention provides methods for manufacturingarticles comprising formulating an acrylic composition wherein amultifunctional chain transfer agent is added to such composition priorto fully curing the acrylic composition.

In another aspect, the invention provides methods for manufacturingarticles comprising formulating a partially cured acrylic composition toform a syrup and then adding a multifunctional chain transfer agent withan isocyanate-reactive group prior to further curing.

In another aspect, the invention provides acrylic compositions having amultifunctional crosslinker capable of bonding directly with anisocyanate-containing composition, and methods for manufacturing thesame.

In another aspect, the invention provides acrylic compositions having amultifunctional chain transfer agent and/or a multifunctionalcrosslinker capable of bonding directly with an isocyanate-containingcomposition, and methods for manufacturing the same.

In another aspect, the invention provides articles comprising cured orsubstantially cured acrylic composition having a multifunctionalcrosslinker or residue thereof directly bound to isocyanate-containingcomposition, and methods for manufacturing the same.

In another aspect, the invention provides acrylic compositions thatfurther include a crosslinker, initiator, and/or additive, and anycombination thereof.

In another aspect, the invention provides a method for improving theefficiency of bonding polyurethane to an acrylic composition, forexample, by avoiding a lamination step.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A A pre-cut side elevation view of an acrylic substrate (or ABS inthe control samples) (A) with polyurethane (B).

FIG. 1B A post-cut side elevation view of an acrylic substrate (or ABSin the control samples) (A) with polyurethane (B) having an overlappingregion (C) of polyurethane and acrylic substrate adhered together at abond interface (D) and having a surface (E).

DETAILED DESCRIPTION OF THE INVENTION

The term “cured” is understood herein to mean that less than 5 wt. % ofthe acrylic composition is residual unreacted monomer, for example, lessthan 3 wt. %, or less than 1 wt. %. The amount of residual unreactedmonomer may be determined by extracting components from a sample of theacrylic composition with methylene chloride and analyzing the extractedcomponents with capillary gas chromatography to identify the amount, inweight % relative to the total acrylic composition, of unreactedresidual monomer.

The present invention comprises acrylic compositions having amultifunctional chain transfer agent capable of bonding directly to anisocyanate-containing composition, and articles and methods ofmanufacturing such articles comprising the acrylic compositions thereof.The present invention comprises articles having an acrylic compositioncapable of bonding to an isocyanate-containing composition by virtue ofan isocyanate-reactive group being present on a multifunctional chaintransfer agent bound within the acrylic polymer matrix. The presentinvention comprises articles having an acrylic composition with amultifunctional chain transfer agent and other components wherein theacrylic composition is directly bound to an isocyanate-containingcomposition. The present invention provides articles comprising anacrylic composition substrate bound to a polyurethane compositionsubstrate wherein the acrylic composition is applied to the polyurethanevia coating and/or coextrusion, or the polyurethane composition isapplied to an acrylic composition substrate via spraying, coating orother means.

Suitable acrylic compositions of the present invention include thosecomprising at least the following components: an α,β-ethylenicallyunsaturated monomer and a multifunctional chain transfer agent.Optionally, the acrylic compositions may additionally comprisecopolymers (including acrylate and non-acrylate), comonomers,crosslinkers, initiators, additives, or combinations thereof.

(1) α,β-ethylenically unsaturated Monomer

Suitable α,β-ethylenically unsaturated monomers include methacrylatemonomers, acrylate monomers, vinyl monomers, and styrene monomers.

Non-limiting examples of suitable methacrylate monomers include:monofunctional methacrylate monomers such as alkyl, for example, C₁ toC₂₀ alkyl, methacrylates, for example, methyl methacrylate, ethylmethacrylate, propyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, iso-butyl methacrylate, t-butyl methacrylate, pentylmethacrylate, 2-ethylhexyl methacrylate, heptyl methacrylate, octylmethacrylate, isooctyl methacrylate, nonyl methacrylate, decylmethacrylate, isodecyl methacrylate, dodecyl methacrylate, tridecylmethacrylate, or undecyl methacrylate; cyclic alkyl methacrylatemonomers such as cyclohexyl methacrylate, isobornyl methacrylate, bornylmethacrylate, tricyclodecanyl methacrylate, dicyclopentanylmethacrylate, dicyclopentenyl methacrylate, cyclohexyl methacrylate,benzyl methacrylate, 4-butylcyclohexyl methacrylate, and dicyclopentenylmethacrylate; and methacrylic acid. Mixtures of more than onemethacrylate monomer may be used.

The acrylic compositions of the present invention include between 0-100wt. % of methacrylate monomer, based on the total weight of monomer.Preferably, the acrylic composition includes greater than about 30 wt.%, such as, for example, 50 wt. % or greater, 80 wt. % or greater, andpreferably 90 wt. % or greater, of methacrylate monomer, based on thetotal weight of monomer. Preferred methacrylate monomers are methylmethacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate and n-butylmethacrylate.

Non-limiting examples of suitable acrylate monomers include methylacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentylacrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, isodecylacrylate, lauryl acrylate, isobutyl acrylate, t-butyl acrylate,2-ethylhexyl acrylate, cyclohexyl acrylate, methylcyclohexyl acrylate,trimethylcyclohexyl acrylate, tertiarybutylcyclohexyl acrylate,isobornyl acrylate, and acrylic acid. Mixtures of more than one acrylatemonomer may be used.

The acrylic compositions of the present invention include between 0-100wt. % of acrylate monomer, based on the total weight of monomer.Preferably, the acrylic composition includes greater than 0.01% ofacrylate monomer. For example, the composition can be 0-50%, 0.01-20%,and preferably 4-6% of acrylate monomer, based on the total weight ofmonomer. Preferred acrylate monomers are methyl acrylate, ethylacrylate,and n-butyl acrylate.

Non-limiting examples of suitable vinyl monomers include N-vinylpyrrolidone, N-vinyl caprolactam, vinyl imidazole, divinyl benzene andderivatives thereof, vinyl pyridine, hydroxybutyl vinyl ether, laurylvinyl ether, cetyl vinyl ether, and 2-ethylhexyl vinyl ether. Mixturesof more than one vinyl monomer may be used.

The acrylic compositions of the present invention include between 0-50wt. % of vinyl monomer, based on the total weight of monomer.Preferably, the acrylic composition includes greater than about 0.01 wt.% of vinyl monomer. For example, the composition can include between1-50 wt. % of a vinyl monomer, such as 2 wt. % or greater, 20 wt. % orgreater, and preferably between 4-6 wt. %, of vinyl monomer, based onthe total weight of monomer. Preferred vinyl monomers are N-vinylpyrrolidone, N-vinyl caprolactam, and vinyl pyridine.

Non-limiting examples of suitable styrene monomers include: styrene andstyrene derivatives, for example, alkyistyrene, hydroxystyrene,halostyrene, alkylhalostyrene, alkoxystyrene, alkyletherstyrene,alkylsilylstyrene and carboxyalkyl styrene. Examples of suitable styrenemonomers for inclusion in the acrylate compositions of the presentinvention include, but are not limited to, methylstyrene,α-methylstyrene, p-methylstyrene, p-hydroxystyrene, m-hydroxystyrene,ethylstyrene, butylstyrene, p-tert-butylstyrene, dimethylstyrene,chiorostyrene, bromostyrene, fluorostyrene, chloromethylstyrene,methoxystyrene, and carboxymethyistyrene. Mixtures of more than onestyrene monomer may be used.

The acrylic compositions of the present invention include between 0-50wt. % of styrene monomer, based on the total weight of monomer.Preferably, the acrylic composition includes greater than about 0.01 wt.% of styrene monomer. For example, the composition can include between1-50 wt. % of a styrene monomer, such as 2 wt. % or greater, 20 wt. % orgreater, and preferably 4-6 wt. %, of styrene monomer, based on thetotal weight of monomer. Preferred styrene monomers are styrene,methylstyrene, α-methylstyrene, p-methyistyrene, p-hydroxystyrene, andm-hydroxystyrene.

The acrylic compositions of the present invention include between 0-99.9wt. % of monomers, based on the total weight of the acrylic composition.Preferably, the acrylic composition includes greater than about 5 wt. %,such as, for example, 7 wt. % or greater, 30 wt. % or greater, andpreferably 50 wt. % or greater of monomers, based on the total weight ofthe acrylic composition. Preferred monomers are methacrylate monomers.

The acrylic composition of the present invention may comprise a mixtureof any of the aforementioned monomers and/or any chemically modifiedmonomers thereof, for example, chemically modified methacrylate, suchthat a chemically modified monomer increases stability of the acryliccomposition.

(2) Multifunctional Chain Transfer Agent

Suitable multifunctional chain transfer agents include compoundscomprising at least one chain transfer moiety and an isocyanate-reactivemoiety. A chain transfer moiety is one that reacts (or is capable ofreacting) with a growing polymer radical causing the growing chain toterminate while creating a new free radical capable of initiating (orre-initiating) polymerization. This re-initiation effectively binds thechain transfer residue to the terminus of the newly forming free radicalpolymer (or terminal to several newly formed free radical polymers ifmore than one chain transfer moieties are present and function totransfer the free radical polymer chain). Often chain transfer moietiesmay also be isocyanate-reactive moieties, suitable multifunctional chaintransfer agents in these instances include those wherein at least twosuch moieties are present such that at least one may serve as a chaintransfer moiety binding with the free radical polymer and at least onefurther remains to serve as the isocyanate-reactive moiety.

Preferred multifunctional chain transfer agents include those whichcomprise at least one thio group and at least one further thio group orother isocyanate-reactive group. Other isocyanate-reactive groupsinclude carboxyl, anhydro, amido, amino, and/or mercapto groups.Non-limiting examples of suitable multifunctional chain transfer agentsinclude those which may be chosen from a range of thiol compounds,including, but not limited to, mercaptocarbonyls, mercaptoesters,mercaptoamines, mercaptocarboxylic acids and mercaptoalcohols, forexample, thioglycollic acid, mercaptopropionic acid, alkylthioglycollates such as 2-ethyl hexyl thioglycollate or octylthioglycollate, mercaptoethanol, mercapto butanol, mercaptoundecanoicacid, thiolactic acid, thiobutyric acid, 2-aminothiophenol,3-aminothiophenol, 4-aminothiophenol, and 6-mercapto-1-hexanol. Inaddition, the multifunctional chain transfer agents may include, but arenot limited to, trifunctional compounds such as pentaerythritoltris(3-mercaptopropionate), pentaerythritol tris(2-mercaptoacetate),trimethylolpropane tris (2-mercaptoacetate), and trimethylol propanetris(3-mercaptopropionate); tetrafunctional compounds such aspentaerythritol tetra(3-mercaptopropionate)(PETMP), pentaerythritoltetra(2-mercaptoacetate), pentaerythritol tetrathioglycollate,pentaerythritol tetrathiolactate, pentaerythritol tetrathiobutyrate;hexafunctional compounds such as dipentaerythritolhexa(3-mercaptopropionate), dipentaerythritol hexathioglycollate;octafunctional thiols such as tripentaerythritolocta(3-mercaptopropionate), tripentaerythritol octathioglycollate.Optionally, the multifunctional chain transfer agent may comprise amixture of more than one multifunctional chain transfer agent.

The acrylic compositions of the present invention include between about0.001 to about 20.0 wt. % of multifunctional chain transfer agent, basedon the total weight of the acrylic composition. For example, the acryliccomposition may include greater than 0.26 wt. %, greater than 0.3 wt. %,greater than 0.4 wt%, greater than 0.5 wt%, and greater than 1.0 wt% ofthe multifunctional chain transfer agent, based on total weight of theacrylic composition. The acrylic composition may include between 0.5-10wt. %, and preferably between 0.01-1 wt. % of the multifunctional chaintransfer agent, based on the total weight of the acrylic composition.Preferred multifunctional chain transfer agents are pentaerythritoltris(3-mercaptopropionate), pentaerythritol tris(2-mercaptoacetate),pentaerythritol tetra(2-mercaptoacetate), pentaerythritoltetra(3-mercaptopropionate), and trimethylolpropane tris(2-mercaptoacetate).

(3) Crosslinker

In addition, the composition of the present invention may include one ormore multifunctional crosslinking agents. Such a crosslinking agent caninclude any multifunctional compounds polymerizable with a methacrylolgroup. Non-limiting examples of such crosslinking agents includediethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate,1,3-butylene glycol dimethacrylate, cyclohexane dimethanoldimethacrylate, diethylene glycol dimethacrylate, dipropylene glycoldimethacrylate, ethylene glycol dimethacrylate, 1,6-hexanedioldimethacrylate, neopentyl glycol dimethacrylate, tetraethylene glycoldimethacrylate, triethylene glycol dimethacrylate, tripropylene glycoldimethacrylate, pentaerythritol trimethacrylate, pentaerythritoltriacrylate, trimethylolpropane trimethacrylate, dipentaerythritolpentamethacrylate, di-trimethylolpropane tetramethacrylate,pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate,divinyl esters such as divinyl adipate, and other divinyl compounds suchas divinyl sulfide or divinyl sulfone compounds of allyl methacrylate,cyclohexanedimethanol divinyl ether diallylphthalate, diallyl maleate,dienes such as butadiene and isoprene, and mixtures thereof.

The acrylic compositions of the present invention include between about0.001 to about 5.0 wt. % of crosslinker, based on the total weight ofthe acrylic composition. For example, the composition can include 0.01wt. % or greater, 0.05, 0.1, 0.5, 1.0 wt. % or greater crosslinkingagent(s), and preferably 0.05, 0.1 or 0.5 wt. % crosslinking agent,based on the total weight of the acrylic composition.

(4) Initiators

The composition of the present invention may also include one or morepolymerization initiators. Non-limiting examples of such initiatorsinclude organic peroxides such as diacyls, peroxydicarbonates,monoperoxycarbonates, peroxyketals, peroxyesters, dialky peroxides,diaryl peroxides, and hydroperoxides, for example, lauroyl peroxide.Also useful are azo initiators, examples of which are:azobisisobutyronitrile, azobisisobutyramide,2,2′-azo-bis(2,4-dimethylvaleronitrile), azo-bis(α-methyl-butyronitrile)and dimethyl-, diethyl- or dibutyl azo-bis(methylvalerate),4,4-azobis(4-cyanovaleric acid), 2,2-azobis-isobutyric acid dimethylester, 1,1-azobis(hexahydrobenzonitrile),2,2′-azobis(2-methylbutyronitrile), 1,1-azo-bis-(isobutyramidine)dihydrochloride, 1,1-azobis(1-cyanocyclohexane),2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane disulfate dihydrate,2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate,2,2′-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride,2,2′-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide},2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride,2,2′-azobis(2-methylpropionamide)dihydrochloride,2,2′-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane],2,2′-azobis{2-methyl-N-[2-(1-hydroxybuthyl)]propionamide},2,2′-azobis(4-methoxy-2,4-dimethyl valeronitrile), dimethyl2,2′-azobis(2-methylpropionate),1,1′-azobis(cyclohexane-l-carbonitrile),1-[(cyano-1-methylethyl)azo]formamide,2,2′-azobis(N-cyclohexyl-2-methylpropionamide),2,2′-azobis[N-(2-propenyl)-2-methylpropionamide], and2,2′-azobis(N-butyl-2-methylpropionamide), and mixtures thereof.

The amount of initiator(s) used can be determined according to thenecessary amount to achieve the desired properties as known to thoseskilled in the art. For example, the acrylic compositions of the presentinvention include between about 0.001 to about 5 wt. % of initiator,based on the total weight of the acrylic composition. Preferably, theacrylic composition includes between 0.01-5 wt. %, or 0.01-2.5 wt. %,based on the total weight of the acrylic composition. For example, theamount of initiator may be 0.01 wt. % or greater, 0.03 wt. %, 0.1 wt. %,1.0 wt. %, or even 2.0 wt. % or greater, and preferably 0.01, 0.03 or0.1 wt. % initiator, based on the total weight of the acryliccomposition.

(5) Additives

In addition to the above components, the present invention can includeone or more additional additives used to regulate various chemical andphysical properties of the composition and/or polymerized articles madetherefrom. Non-limiting examples of such additives include: lubricants,stabilizers, coupling agents, matting agents, toners, anti-foggingagents, fading inhibitors, thermal stabilizers, antioxidants, metalscavengers, fluorescent whiteners, surfactants, plasticizers, flame/fireretardants, dye precursors, fungicides, antimicrobial agent, includingMicroban™ (triclosan), antistatic agents, magnetic substances,deglossers, organic deglossers, polymeric deglossers, processing aid, UVabsorbers, and UV stabilizers.

The acrylic compositions of the present invention include between about0.001 wt. % to about 10.0 wt.% of the aforementioned additive(s), basedon the total weight of the acrylic composition. For example, the amountof additive(s) may be from about 0.01 wt. % to about 5 wt. %, or 0.1 wt.% to about 2.5 wt. %, based on the total weight of the acryliccomposition. Also, the amount of additive may be 0.01 wt. % or greater,0.03 wt. %, 0.1 wt. %, 1.0 wt. %, or even 2.0 wt. % or greater, andpreferably 0.01, 0.03 or 0.1 wt. % additive, based on the total weightof the acrylic composition.

In some embodiments of the present invention, the acrylic compositionmay also comprise an impact modifier. The impact modifier resin added,for example by blending, to the acrylic composition is in an amountcorresponding to about 1 wt. % to about 70 wt. %, preferably 5 wt. % to50 wt. %, based on the total weight of the acrylic composition. Impactmodifiers include those comprising one of several different rubberymodifiers such as graft or core shell rubbers or combinations of two ormore of these modifiers. Non-limiting examples of impact modifiers areillustrated by acrylic rubber, ASA rubber, diene rubber, organosiloxanerubber, ethylene propylene diene monomer (EPDM) rubber,styrene-butadiene-styrene (SBS) rubber,styrene-ethylene-butadiene-styrene (SEBS) rubber,acrylonitrile-butadiene-styrene (ABS) rubber,methacrylate-butadiene-styrene (MBS) rubber, styrene acrylonitrilecopolymer, and glycidyl ester impact modifier. Suitable impact modifiersare graft or core shell structures with a rubbery component with a T_(g)below 0° C., preferably between about −40° C. to 80° C., composed ofpoly alkylacrylates or polyolefins grafted with polymethylmethacrylate(PMMA) or styrene acrylonitrile (SAN). Any rubber may be used as animpact modifier as long as the impact modifier does not negativelyimpact the physical or aesthetic properties of the acrylic composition.Mixtures of more than one impact modifier may be used.

In some embodiments of the present invention, the acrylic compositionmay also comprise a visual effect enhancer, including colorant, dye, orpigment, which may be present in an encapsulated form, anon-encapsulated form, or laminated to a particle comprising polymericresin. Visual effect enhancers in encapsulated form usually comprise avisual effect material such as a high aspect ratio material likealuminum flakes encapsulated by a polymer. The encapsulated visualeffect enhancer has the shape of a bead.

Some non-limiting examples of visual effect enhancers are aluminum,gold, silver, copper, nickel, titanium, stainless steel, nickel sulfide,cobalt sulfide, manganese sulfide, metal oxides, white mica, black mica,pearl mica, synthetic mica, mica coated with titanium dioxide, andmetal-coated glass flakes. Dyes, including fluorescent dyes, may also beused. Pigments such as titanium dioxide, zinc sulfide, carbon black,cobalt chromate, cobalt titanate, cadmium sulfides, iron oxide, sodiumaluminum sulfosilicate, sodium sulfosilicate, chrome antimony titaniumrutile, nickel antimony titanium rutile, and zinc oxide may be employed.

Additionally, visual effect enhancers may include particles of polymericmaterial such as polyethylene or polypropylene, anacrylonitrile/butadiene/styrene copolymer, or a poly(ethyleneterephthalate) polymer. In another embodiment of the present invention,the polymeric particle comprises a polyalkyl (meth)acrylate or acopolymer of two or more polyalkyl (meth)acrylates. Also, the particlesmay comprise multifunctional methacrylate monomers, for example, a(C₂-C₁₈)alkanediol dimethacrylate, and, in another embodiment, a(C₄-C₈)alkanediol methacrylate. In another embodiment, the particle maycomprise a polymer selected from the group consisting of 1,2-ethanedioldi(meth)acrylate; 1,3-propanediol di(meth)acrylate; 1,4-butanedioldi(meth)acrylate; 1,5-pentanediol di(meth)acrylate; 1,6-hexanedioldi(meth)acrylate; 1,8-octanediol di(meth)acrylate; and 1,10-decanedioldi(meth)acrylate, and, more preferably, the polymer comprises1,6-hexanediol diacrylate (“HDDA”) or 1,4-butanediol diacrylate. In oneembodiment of the invention, the particles are composed of cross-linkedpolymers, for example, a cross-linked polyacrylate, which may be derivedfrom a continuous cast cross-linked polymer sheet. In anotherembodiment, the particle comprises a polymer of an aromatic monomer.Non-limiting examples of aromatic monomers include, but are not limitedto: styrene; divinylbenzene; divinylnaphthalene; diallyl phthalate; andN,N-divinyl aniline.

When polymeric particles are used in the present invention, suchparticles may be cured after they are formed by polymerization. Curingmay be by any suitable means, such as chemical or heat curing. Mixturesof more than one visual effect enhancer may be used.

The acrylic compositions of the present invention may include betweenabout 0.01 to about 40 wt. % of visual effect enhancer(s), based on thetotal weight of the acrylic composition. A preferred acrylic compositionmay include between 0.1-30 wt. %, and more preferably between 1-20 wt.%, based on the total weight of the acrylic composition. A mixture ofdifferent visual effect enhancer particles may be used to providedifferent appearances, e.g. to simulate the appearance of naturalmaterials such as stone or granite.

In some embodiments, the present invention may comprise a filler such asmineral filler. Mineral filler is a particulate mineral compound. Theacrylic composition may contain 5-90 wt. % of the filler, preferably10-80 wt. %, for example, about 67 wt. %, based on the total weight ofthe acrylic composition. A mixture of more than one mineral compound maybe used as the filler.

The type and amount of additives used throughout the invention can bedetermined according to the necessary amount to achieve the desiredproperties as known to those skilled in the art.

Polymerization of Acrylate

The acrylic compositions can be made by conventional free radical orother polymerisation techniques, for example bulk, solution, emulsion,dispersion, or suspension, in combination with other techniques such ascell-casting. Monomer(s) are caused to polymerise by initiating thepolymerisaton reaction, normally by means of activating the addedinitiator, and maintaining suitable conditions, e.g. an elevatedtemperature, pressure etc. until the required degree of polymerisationhas been achieved. Such methods are already well known to the skilledperson and a large number of such methods exist in the art.

The acrylic composition resulting from the polymerization may be in amultitude of forms including, powder, pellets, syrup (partially cured),suspension, solution, emulsion, film, resin, and sheet. Each of theseaforementioned forms may be partially or fully cured.

Isocyanate-Containinq Composition

The acrylic composition, described above, may be cured or partiallycured prior to applying an isocyanate-containing composition onto theacrylic composition. Alternatively, the isocyanate-containingcomposition can be formed first, for instance as a substrate.Isocyanate-containing compositions may include urethane-containingcompositions, such as a mixture of polyurethane, polyol, andunreacted-isocyanate groups. A preferred isocyanate-containingcomposition is polyurethane. These are primarily formulated frompolyisocyanates and polyols. Although other suitableisocyanate-containing compositions may work, the preferredisocyanate-containing composition is prepared by mixing polyol andpolyisocyanate components and allowing the reactants to react and form apolyurethane. In some instances, polyisocyanates are mixed with a smallamount of polyols and allowed to react to form a prepolymer ofpolyurethane. This prepolymer is often formed to allow for greaterstability of the isocyanate component during shipping and handling.

(1) Polyisocvanate

Typically, polyisocyanates include aromatic, cycloaliphatic and/oraliphatic polyisocyanates.

Non-limiting examples of suitable aromatic polyisocyanates include: anyisomers of toluene diisocyanate (TDI) either in the form of pure isomersor in the form of a mixture of several isomers,naphthalene-1,5-diisocyanate (NDI), naphthalene-1,4-diisocyanate (NDI),4,4′-diphenylmethane-diisocyanate (MDI),2,4′-diphenylmethane-diisocyanate (MDI), xylylenediisocyanate (XDI),2,2-diphenylpropane-4,4′-diisocyanate, p-phenylene diisocyanate,m-phenylene diisocyanate, diphenyl-4,4′-diisocyanate,diphenylsulphone-4,4′-diisocyanate, 1-chlorobenzene-2,4-diisocyanate,4,4′,4″-triisocyanato-triphenyl-methane, 1,3,5-triisocyanato-benzene,2,4,6-triisocyanato-toluene, furfurylidene diisocyanate, and mixturesthereof.

Non-limiting examples of suitable cycloaliphatic polyisocyanates include4,4′-dicyclohexylmethane diisocyanate (H₁₂ MDI),3,5,5-trimethyl-3-isocyanatomethyl-1-isocyanato-cyclohexane(isophorone-diisocyanate, IPDI), cyclohexane-1,4-diisocyanate,cyclohexane-1,2-diisocyanate, hydrogenated xylylene diisocyanate (H₆XDI), m- or p-tetramethylxylylene diisocyanate (m-TMXDI, p-TMXDI),diisocyanate from dimer acid, and mixtures thereof.

Non-limiting examples of suitable aliphatic isocyanates includehexane-1,6-diisocyanate (HDI), 2,2,4-trimethylhexane-1,6-diisocyanate,2,4,4-trimethylhexane-1,6-diisocyanate, butane-1,4-diisocyanate and1,12-dodecane diisocyanate (C₁₂ DI). Particularly preferred for maximumformulation stability is a liquid mixture of4,4′-diphenylmethane-diisocyanate, 2,4′-diphenylmethane-diisocyanate,and mixtures thereof.

(2) Polyol

Typically, polyols for making the polyurethane composition may beselected from polyetherpolyols, polyester polyols and/or aromaticpolyols.

A polyether polyol is understood to be a linear polyether containingpredominantly two OH groups. The preferred polyether polyols are diolscorresponding to the general formula HO(—R—O)_(m)—H, where R is ahydrocarbon radical containing 2 to 4 carbon atoms and m is in the rangefrom 4 to 225 on average. Non-limiting examples of such suitablepolyether polyols include polyethylene glycol, polybutylene glycol,polytetramethylene glycol (polyTHF) and, above all, polypropylene glycol(R═—CH)₂CH(CH₃)—). Such polyether polyols may be prepared by knownmethods such as, for example, polymerization of one or more cyclic ethermonomers such as ethylene oxide, propylene oxide, n-butene oxide, andtetrahydrofuran. The polyether polyols may be used both as homopolymersand as copolymers, both as block copolymers and as statistical (random)copolymers. Only one type of polyether polyol is preferably used,although mixtures of 2 to 3 polyether polyols differing in their averagemolecular weight and/or in the nature of their structural elements mayalso be used. Small quantities of a trifunctional polyether polyol(i.e., a polyether triol) may also be present in the mixture. Theaverage molecular weight (number average molecular weight) of thepolyether polyols is in the range from 200 to 10,000 and preferably inthe range from 400 to 6,000.

A polyester polyol is understood to be a polyester having more than 1 OHgroup, preferably 2 terminal OH groups. Preparation is by known routes,either from a) aliphatic hydroxycarboxylic acids, or from b) aliphaticand/or aromatic dicarboxylic acids having from 6 to 12C atomsand—particularly even-numbered—diols having from 4 to 8C atoms.

An aromatic polyol is understood to be an alkoxylation product of anaromatic polyhydroxy compound. These are, in particular, the reactionproducts of ethylene oxide and/or propylene oxide with aromaticdihydroxy compounds such as, for example, hydroquinone, resorcinol,pyrocatechol, bis-(hydroxydiphenyl), bisphenol A, bisphenol F, isomersof dihydroxynaphthalene (pure isomers or a mixture of several isomers),isomers of dihydroxyanthracene (pure isomer or isomer mixture) orisomers of dihydroxyanthraquinone.

The isocyanate-containing compositions of the present invention mayinclude an excess amount of isocyanate to polyol. For example, theisocyanate may range from about 1.01 to about 10.0 moles, about 1.1 toabout 5.0 moles, and about 1.2 to about 2.0 moles, to each 1 mole ofpolyol. Preferably, the amount of isocyanate is about 1.4 to about 1.6moles relative to the moles of polyol.

Adhesion Test

The adhesion, i.e., bond strength, required between a polyurethanecomposition substrate and an acrylic composition substrate in an articleis that amount which is necessary to maintain adhesion during the normalcourse of shipping, handling, installation and/or use of the article fora duration of time, for example, over many years. Such adhesionrepresents “commercially acceptable” adhesion. Presently, in themarketplace, systems comprising an acrylic composition linked topolyurethane by an ABS laminate have superior adhesion. Articles of thepresent invention have at least “commercially acceptable” adhesion andpreferably have at least superior adhesion or better than superioradhesion.

Uses

In some embodiments, the acrylic composition of the present inventionmay be prepared in a variety of forms to facilitate their use in methodsof the present invention. For example, the acrylic compositions may beformed into acrylic sheet or sheet molding compounds (SMC), for exampleby techniques known in the art such as cell cast, continuous cast,and/or extrusion, for use in thermoforming processes. Alternatively, theacrylic compositions may be formed into pellets that are useful forapplications that involve extrusion, coextrusion and/or pultrusion.Additionally, the acrylic compositions may be in the form of a powderfor various coating applications and for use in paints or other coatingapplications, with or without solvents or suspending agents such asfillers.

In some embodiments, methods of the present invention include methods ofapplying a polyurethane composition to an acrylic substrate formed froman acrylic composition as discussed above. In some embodiments, thesubstrate may be in the form of an acrylic sheet or sheet moldingcompound or may be an article formed or thermoformed from acrylic sheetor sheet molding compound. Non-limiting examples of thermoforminginclude injection molding, vacuum suction, blow molding, and plugassisted. The polyurethane may be applied directly to the acrylicsubstrate as a coating, film or spray and may bond and/or exhibit goodadhesion to the acrylic substrate. For example, the polyurethane may beapplied to a surface of a shaped acrylic article such as a bath, vanity,sink, spa, shower, shower tray, container, sign, lighting, fixture,architectural component such as a window profile, or building materialto provide various desirable properties discussed herein.

In other embodiments, the acrylic composition may be applied to apolyurethane substrate. In some embodiments, the acrylic composition maybe in the form of pellets that may be extruded or co-extruded with apolyurethane to form an acrylic coated polyurethane article or anacrylic capped polyurethane article such as, but not limited to,building materials (e.g., siding, window lintels, walls, work surface)and mechanical parts (e.g., car parts). For example, polyurethane can beformed by pultrusion into various articles and acrylic capped with amore or less simultaneous extrusion of an acrylic composition of thepresent invention. In some embodiments, the acrylic composition isapplied, for example extruded, to a virgin or recently formedpolyurethane substrate such as within 30 minutes, for example less than10 minutes, after the polyol and polyisocyanate are mixed.

In other embodiments, the acrylic composition may be in the form of apowder, a suspension, an emulsion, a powder in a solvent or a solutionsuch as a paint, coating and/or ink, and may be applied to apolyurethane substrate by coating, capping, painting, spraying or otherconventional coating techniques. For example, the acrylic compositionmay be applied to siding, window lintels, walls, polyurethane-containingparticle board articles such as furniture and shelves, architecturalcomponents such as moldings, work surfaces and appliances to form anarticle comprising one or more acrylic layers bound to a polyurethanesubstrate.

In some embodiments, the acrylic composition may be custom-coloredand/or adapted to be heat-tolerant.

EXAMPLE

The following examples are given as particular embodiments of theinvention to demonstrate the practice and advantages thereof. It is tobe understood that the examples are given by way of illustration and arenot intended to limit the specification or the claims that follow in anymanner.

Example 1 Comparative Samples A-B and Inventive Samples 1-3 Chisel Test

A series of cured acrylic substrate samples were prepared and thesurface of the samples was cleaned with acetone and dried. The acrylicsamples were then sprayed with the a two-component polyurethane mixture(Isotec TP1155-4 from Isotec International which comprises a polymericMDI (CAS 9016-87-9) and a proprietary mix of polyols and an aminecatalyst). The acrylic/polyurethane article was then cut into one-halfinch strips. The adhesive strength between the acrylic and polyurethanelayers was tested by using a chisel hammer (1.5 lb with a 12″ handle)directed at the interface of the two layers. See Table 1.

TABLE 1 Adhesive Strength Between a Polyurethane Layer and an AcrylicLayer As a Function of Using Acrylic Formulations with a MonofunctionalChain Transfer Agent vs. Acrylic Formulations with a MultifunctionalChain Transfer Agent Chain Transfer Agent Monofunctional Lauryl AcrylicMercaptan Polyfunctional Sample Description (wt. %) PETMP (wt. %)Cleaved Apart A (control) Lucite XL ™ 0 0 Adhesive Failure BN6528 B(control) Lucite ™ 0.20 0 Adhesive Failure Celestial Granite ™ 1Lucite ™ 0 0.25 Partial Cleavage Celestial (Adhesive/Cohesive) Granite ™2 Clear 0 0.45 No Cleavage Extruded Sheet 3 White 0 0.45 No CleavageExtruded Sheet

In both control samples A and B, the two layers cleanly and easilyseparated via an adhesive failure mode between the two layers. Sample 1was partially unable to be cleaved (good bond strength). Samples 2 and 3were unable to be cleaved (high bond strength).

Example 2 Comparative Samples C-D and Inventive Samples 4-5 Peel Test

A series of acrylic-polyurethane test specimens were prepared. See Table2. Adhesive strength was determined by using a fixed arm peel test. Theisocyanate-containing composition of the polyurethane substrate had a1.5:1.0 molar ratio of isocyanate to polyol, respectively.

Specimens for conducting the fixed arm peel test were rectangular shapedwith dimensions of 40 mm×110 mm. The thickness of the polyurethane,which was used as the peel arm, and acrylic substrate were approximately4 mm and 3.2 mm, respectively. A razor blade was used initially to splitthe interface (D) of the specimens to establish a peel fracture. Theacrylic substrate side of the specimens was adhered to a peel table.

A peel jig was used to separate the two layers. The peel jig was fixedto the top of the unadhered material of the polyurethane peel arm. Theangle between the substrate and the peel arm was fixed at 60°. The jigwas attached to an Instron 5565 testing machine, so that as peel occursthe peel angle is maintained constant by the jig moving along a lowfriction linear bearing system. A 100 N load cell was used. The peeltest speed was 10 mm/min. The force versus displacement (J/m²) wasrecorded for each sample.

TABLE 2 Adhesive Strength Between a Polyurethane Substrate on an AcrylicSubstrate As a Function of Using Acrylic Formulations with aMultifunctional Chain Transfer Agent or Multifunctional CrosslinkerChain Transfer Agent Crosslinker 3- Pentaerythritol- Adhesive Acrylicaminothiophenol triacrylate Strength Sample Description (wt. %) (wt. %)(J/m²) C GR7121 0 0 53 (control) Starry night D WT6064 0 0 62 (control)4 GR7121 + 0.15 0 121 chain transfer agent 5 WT6064 + 0 0.1465 95crosslinker Test Notes: GR7121 Starry night is a Celestrial GraniteAcrylic Sheet, available from Lucite. WT6064 is a Lucite XL ™ acrylicbath sheet, available from Lucite.

Example 3 Comparative Samples E-I and Inventive Samples 6-15 CompressiveSheer Test

A series of acrylic-polyurethane test specimens were prepared. See Table3. Bond strength was determined by using a compressive sheer test. Theamount of isocyanate was in excess relative to the amount of polyol.

The samples were conditioned for approximately forty hours at 23° C.±2°C. and tested at 23° C.±2° C. The exposed perpendicular surfaces (E) ofthe polyurethane substrate (B) and acrylic substrate (or ABS in thecontrol samples) (A) of the overlapping region (C) in the post-cutspecimens were loaded by means of a compression shear fixture havingself-aligning loading faces. See FIGS. 1A and 1B. A cross-head rate of0.020 inch per minute was used. Bond strength was measured as a functionof cleavage at the bond interface (D) between the polyurethane substrate(B) and acrylic substrate (or ABS in the control samples) (A) in theoverlapping region (C). Maximum compressive strength represented maximumforce at specimen failure.

TABLE 3 Bond Strength Between a Polyurethane Substrate on an AcrylicSubstrate As a Function of Using Acrylic Formulations with aMultifunctional Chain Transfer Agent vs. ABS A B Maximum Maximum ChainTransfer Acrylic Polyurethane C Compressive Compressive Agent PETMPThickness Thickness Width Length Strength Strength D Description Sample(ppm) (in.) (in.) (in.) (in.) (lbf) (psi) Bond Strength GR-7121 + E 00.146 0.236 0.999 0.506 1670 3300 No Failure ABS and F 0 0.140 0.2360.999 0.509 1490 2920 No Failure Polyurethane G 0 0.135 0.235 1.0040.504 1390 2740 Bond Failure (Control) H 0 0.150 0.234 1.005 0.508 15302990 No Failure I 0 0.148 0.236 0.996 0.500 1510 3030 No FailureGR-7121 + 6 2538 0.144 0.155 1.005 0.507 1680 3310 Partial Bond FailurePETMP and 7 2538 0.145 0.155 0.995 0.500 1560 3140 Partial Bond FailurePolyurethane 8 2538 0.143 0.154 1.007 0.508 1730 3380 Partial BondFailure 9 2538 0.143 0.153 1.006 0.512 1640 3180 Bond Failure 10 25380.139 0.156 1.007 0.509 1900 3720 Partial Bond Failure 11 4500 0.1420.176 1.004 0.512 1780 3460 No Failure 12 4500 0.140 0.181 1.004 0.5101860 3640 No Failure 13 4500 0.142 0.180 1.004 0.512 1710 3320 NoFailure 14 4500 0.146 0.175 1.004 0.507 1750 3440 No Failure 15 45000.139 0.181 1.004 0.510 1810 3540 No Failure

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by referenceherein in its entirety.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

1-16. (canceled)
 17. An article comprising: (a) an acrylic compositionhaving bound therein at least one residue of a multifunctional chaintransfer agent, wherein said multifunctional chain transfer agentresidue comprises a reacted isocyanate-reactive group that has beenreacted to an isocyanate within an isocyanate-containing composition.18. (canceled)
 19. An article comprising an acrylate composition bondedto a polyurethane composition, wherein said bond is formed between aresidue of an isocyanate-reactive group bound within said acryliccomposition and a residue of an isocyanate bound within saidpolyurethane composition. 20-25. (canceled)
 23. An article comprising:(a) an acrylic composition having bound therein at least one residue ofa multifunctional crosslinker, wherein said multifunctional crosslinkerresidue comprises a reacted isocyanate-reactive group that has beenreacted to an isocyanate within an isocyanate-containing composition.24-25. (canceled)